Apparatus for the production of artificial silk



Jan. 24, 1939. W GN R 2,144,785

I APPARATUS FOR THE PRODUCTION OF ARTIFICIAL SILK Filed Nov. 8,1955 2 Sheets-Sheet 1 17 Z i612 fik yyzer Q M My Jan.24, 1939. AGN 2,144,785,"

APPARATUS FOR THE PRODUCTION OF ARTIFICIAL SILK Filed Nov. '8, i935 2 Sheets-Sheet 2 Affarzzgy Patented Jan. 24, 1939 UNITED STATES PATENT OFFICE APPARATUS FOR THE PRODUCTION OF ARTIFICIAL SILK bahn, Germany Application November 8, 1935, Serial No. 48,907 In Germany November 19, 1934 3 Claims.

The present invention relates to a process and apparatus for the production of artificial fibres by a new stretch-spinning method.

An apparatus is already known by means of 5 which a group of filaments can be spun, without negative pressure in the spinning bowl, by the aid of a freely suspended columnof precipitant liquid, the thickness of the resulting filament bundle being a function of the aperture of the discharge nozzle for the precipitant.

It is also known to allow the filament leaving the first precipitation bath to pass through additional baths, for secondary coagulation or washing, by using bowls arranged one below another, but in all the known processes the drawing and final stretching are effected by mechanical means, such as conveyor wheels, bobbins, reels and the like situated outside the bowls.

In the known spinning processes, the elemental filaments remain more or less adherent after stretching. The finished and stretched soft elemental filaments, which are still plastic, readily stick together, and the subsequent acid treatment does not effect the separation of this undesirable union, but rather tends to accentuate it.

By contrast, the invention is chiefly concerned with the formation and subsequent treatment of soft and woolly filaments without mechanical means.

The exclusive treatment in the precipitant liquid during the formation of the filaments enables the operation to be carried on at a high velocity (about 100 metres per minute) in such a manner that the filament is not drawn oil, but descends with the current of precipitant, owing to the velocity of the latter. An object of the invention is to provide apparatus for the production of cuprammonium silk fibre by the stretch-spinning method comprising in combina- 40 tion with a spinning bowl, a spinning nozzle having a group of jets downwardly directed into the upper end of the bowl, a discharge nozzle at the lower end of the bowl, means causing precipitant liquid to descend continuously, without negative pressure, through said bowl and its discharge nozzle, and means expressing the filamentary jets of cellulose solution through the spinning nozzle into the descending precipitant, of a downwardly tapering vessel disposed below said discharge nozzle, a discharge orifice at the bottom of said vessel, and means causing the precipitant to descend continuously, also without negative pressure, through said vessel wherein it serves to stretch the bundle of filaments 56 emerging fro-m said discharge nozzle, a precipitant collecting bath disposed below said discharge orifice, and an endless band passing through said bath for transporting the stretched filament bundle at reduced speed whereby said bath and band serve to relax the tension of the filament bundle.

The stretch-spinning treatment afforded by said apparatus, which is far more protective than the known methods in that it entirely avoids mechanical drawing, has the advantage that the bundle of filaments is finally rendered softer and wool-like in character, though remaining satisfactorily firm.

It is known to employ, for secondary treatment and washing, an apparatus characterized by a series of treatment baths, with intermediately disposed pairs of squeezing rollers of different peripheral velocities, in order that the filament bundle may be in an unstretched condition during its passage through the baths. In that case, the loosening is performed for the purpose of rendering the filaments more accessible to the liquid in the secondary treatment. The invention is entirely difierent in that the aforesaid checking and relaxing stage of the process according to the invention takes part in the formation of the filament.

It is also known to employ cylindrical screens for the secondary treatment of artificial silk in such a manner that the filament, in describing a spiral course, is treated with a plurality of liquids that are brought separately into action on the filament. According to the invention, on the contrary, the filament is passed over a heated, cylindrical vacuum screen, in order to remove the adherent precipitant and the ammo-nia contained therein, and in the second place, to effect a fixation, or secondary hardenmg.

After passing over the heated, cylindrical screen, the filaments are wound in hank form alternately on round winding drums, over which they run without kinking.

The result of the high rate of draft is that neither small bobbins nor the usual reels are applicable for taking up the oncoming filaments in a suitable manner,

The raw fibres which have been wound in parallel arrangement on the large drum may be cut up, the length of the staple depending on the existing conditions in the spinning works, and being usually about 30-40 mm. The staple fibres are then put through an opener, in which they are loosened, either alone or in admixture with cotton or wool. They are next put through an opener combined with a beater, to furnish a compact fleece which, after several passages through the beater, is converted into a second lap, finer and more uniform than the first. This lap is then put through the cotton carder, for example, and passed repeatedly through the coarse, medium and fine drawing frames. The sliver is then simply put through the slubbing, intermediate and roving frames and finally taken to the spinning frame which turns out the finished yarn.

The fibres wound in parallel on the drum may also be transferred directly to the comber or cotton drawing frame, without being out, the machine delivering a completely straightened rove.

According to another feature of the invention, when the yarn is cross-wound on the drum in known manner, the aforesaid working stages may be eliminated, the fibre coming direct from the reel being formed, on the doubling frame, into a yarn which complies with the most stringent requirements in respect of quality.

The fibre may be worked up as a cotton substitute, which is produced cheaply in the manner last described, eliminating the first cutting and deforming of the fibre and employing the exceedingly soft fibres, formed in accordance with the above process, and having a handsome dull sheen and fluffy character, directly for further manufacturing treatment.

As the result of the open filament being present in the strand, the latter acquires the woolly character that is imparted to cut goods by protruding fibrils.

It should be mentioned that the temperature and chemical composition of the precipitant liquid, and also the volume of the flow, are factors which modify the quality of the fibre.

When the endless hank is cross-wound on the reel, there results a further opening up of the filament on unreeling, so that the woolly character is retained, and even increased, without the fibre being injuriously weakened.

Apparatus for carrying out the process according to the invention is illustrated, by way of example, in the accompanying diagrammatic drawings.

Fig. l is a cross-section of apparatus for spinning and subsequently treating fibres according to the invention,

Fig. 2 is a front elevation, partly in section, of the spinning portion of the apparatus, and

Fig. 3 illustrates a detail.

For the first mentioned process, the apparatus according to Figs. 1 to 3 comprises a pipe 1 containing the cellulose solution, and furnished with a plurality of discharge nozzles 2 adapted to be swung for filling and cleaning, which is advisable in a multiple-nozzle arrangement as shown. The bowl head it is so designed as to provide accommodation for any convenient large number of juxtaposed spinning bowls 3.

In this bowl head W, with its large superficies, the precipitant liquid flows in a uniform and quiet manner into all the spinning bowls 3 inserted in said head. In conjunction with the nozzle apertures 5 of the spinning bowls 3, the height of the precipitant in the head to, above the whole of the spinning bowls, determines the rate of discharge of the filaments. From the pipe I, the cellulose solution flows, under pressure, into the nozzle heads 2 and thence through groups of jets into the precipitant-filled spinning bowls 3. The

newly formed filaments pass in bundles from the spinning bowls 3, through the nozzles 5 of the latter, with the currents of precipitant, into, a trough 6 underneath, said trough being provided with partitions i3 (Fig. 2) to prevent the.

several filament bundles from coalescing and being fed with an additional quantity of the same precipitant to maintain a head therein as shown.

'The delivery outlet 1 of the trough 6 is adjustable,

and the precipitant is caused to flow therethrough at a velocity that is substantially higher than its velocity of descent in the spinning bowls 3, in consequence of which the filaments 4 are subjected to additional stretching, the degree of elongation depending on the setting of the outlet 1.

From the trough 6, the filaments and precipitant pass into a collector bath 9 underneath, in which the filaments are received on an endless belt conveyor 8. The strands l9 of filament are relaxed by the precipitant present in the collector, and conveyed, in that condition, over a guide roller 22 to a suction screening cylinder H, by means of which the precipitant (and its contained ammonia) adhering to the filaments is removed as completely as possible. Gas drawn into the cylinder I I by the vacuum is recovered in known manner. This purpose is substantially favoured by a heating coil 20 provided in the vessel.

The vessel 2| has a conical bottom, to enable the collected copper hydroxide to be drawn oif and returned tothe dissolving process. It carries a guide 2! which directs the filaments on to cylindrical drums l2 and I3 alternately, on which the strands of filament are wound, either crosswise or parallel, until a certain depth of layer has been attained, whilst, at the same time, the filaments are washed in sulphuric acid, sprayed upon them through nozzles l4.

When the required depth of layer has been attained, the filaments are cut away from the winding drums. The resulting cakes 15 are then superimposed in several layers in a washing vessel l 6, as shown in Fig. 3, on perforated plates I1 and treated with liquids in succession. The treatment may be performed under the usual conditions, though preferably in a vacuum trough. Two soapings are given.

The cakes are dried and mangled, either at ordinary or higher temperature, and with smooth or fluted rollers. By this means, a perfectly soft and open, smooth or undulating (woolly) fibrous material is obtained, which can be cut into any convenient known lengths of staple.

I claim:

1. Apparatus for the production of cuprammonium silk fibre by the stretch-spinning method comprising the combination with a spinning bowl, a spinning nozzle having a group of jets downwardly directed into the upper end of the bowl, a discharge nozzle at the lower end of the bowl, means causing precipitant liquid to descend continuously, without negative pressure, through said bowl and its discharge nozzle, and means expressing filamentary jets of cellulose solution through the spinning nozzle into the descending precipitant, of a downwardly-tapering vessel disposed below said discharge nozzle, a discharge orifice at the bottom of said vessel, means causing the same precipitant to descend continuously, also without negative pressure, through said vessel wherein it serves to stretch the bundle of filaments emerging from said discharge nozzle, a precipitant-collecting bath disposed below said discharge orifice, and an endless band passing through said bath for transporting the stretched filament bundle at reduced speed whereby said bath and band serve to relax the tension of the filament bundle.

2. Apparatus for the production of cuprammonium silk fibre by the stretch-spinning method comprising the combination with a spinning bowl, a spinning nozzle having a group of jets downwardly directed into the upper end of the bowl, a discharge nozzle at the lower end of the bowl, means causing precipitant liquid to descend continuously, without negative pressure, through said bowl and its discharge nozzle, and means expressing filamentary jets of cellulose solution through the spinning nozzle into the descending precipitant, of a downwardly-tapering vessel disposed below said discharge nozzle, a discharge orifice at the bottom of said vessel, means causing the same precipitant to descend continuously,

= also without negative pressure, through said vessel wherein it serves to stretch the bundle of filaments emerging from said discharge nozzle, a precipitant-collecting bath disposed below said discharge orifice, an endless band passing through said bath for transporting the stretched filament bundle at reduced speed whereby said bath and band serve to relax the tension of the filament bundle, a drying chest, a heating coil in said chest, a vacuum screen rotatable in said chest, guide means serving to guide the filament from said bath over said cylinder, means for reeling the dried filament, and means for spraying acid on the filament during reeling.

3. Apparatus for the production of cuprammonium silk fibre by the stretch-spinning method comprising the combination with a spinning bowl, a spinning nozzle having a group of jets downwardly directed into the upper end of the bowl, a discharge nozzle at the lower end of the bowl, means causing precipitant liquid to descend continuously, without negative pressure, through said bowl and its discharge nozzle, and means expressing filamentary jets of cellulose solution through the spinning nozzle into the descending precipitant, of a downwardly-tapering vessel disposed below said discharge nozzle, means causing the same precipitant to descend continuously, also without negative pressure, through said vessel in the upper part of which it serves to stretch the bundle of filaments emerging from said discharge nozzle, a discharge tube at the bottom of said vessel and bent through approximately a right angle to retard the precipitant in the lower part of said vessel and thereby relax the tension of the previously stretched filament in said lower part, a precipitant-collecting bath disposed about said discharge tube, a drying chest, a heating coil in said chest, a perforated suction, a vacuum screen rotatable in said chest, guide means serving to guide the filament from said bath over said cylinder, a winding drum for receiving the dried filament and means for spraying acid on the filament during winding on said drum.

ALBERT WAGNER. 

